It is known to utilize interchangeable arc or other shaped nozzles in sprinklers in order to modify the pattern wetted by the discharge stream, while maintaining a constant flow or precipitation rate in the wetted areas. Typically, these nozzles comprise orifice plates which have a central hole for receiving a shaft that supports the distributor above the nozzle. The orifice itself is generally radially outwardly spaced from the shaft hole in the orifice plate. Representative examples of this type of construction are found in U.S. Pat. Nos. 4,967,961; 4,932,590; 4,842,201; 4,471,908; and 3,131,867. Other arc adjustment techniques are described in U.S. Pat. Nos. 5,556,036; 5,148,990; 5,031,840; 4,579,285; and 4,154,404. It is also known to incorporate adjustable flow rate arrangements in sprinklers, within the context of substantially constant water pressure. For example, see U.S. Pat. Nos. 5,762,270; 4,898,332; and 4,119,275. Such arc adjustment and flow rate adjustment features are often incorporated into pop-up sprinklers. Examples of pop-up sprinklers are found in U.S. Pat. Nos. 5,288,022; 5,058,806; 4,834,289; 4,815,662; and 4,790,481.
Commonly owned U.S. Pat. Nos. 6,651,905 and 6,736,332 (both of which are incorporated in their entirety herein by reference) disclose sprinkler heads designed especially (but not exclusively) for use with pop-up type sprinklers configurations, and that provide within limits, essentially infinite arc adjustment and throw radius adjustment features, and at the same time, constant precipitation rates and good uniformity. These sprinklers also minimize suckback plugging of the nozzle; permit active cleaning of the nozzle, and minimize potential damage to critical internal components when, for example, impacted during use.
The sprinkler heads in the '905 and '332 patents generally include a nozzle and a rotary water distribution plate (or rotor plate) mounted on a shaft so as to be axially spaced from the nozzle. The rotor plate is formed with a plurality of curved, generally radial grooves that cause the rotor plate to rotate when impinged upon by a hollow, generally cone-shaped stream emitted from the nozzle. The rotor plate may incorporate a viscous damping mechanism to slow its rate of rotation.
In the pop-up embodiments, the nozzle and associated stream deflector are supported within a hollow stem which, in turn, is supported within a cylindrical base. A coil spring is located axially between a flange at the upper end of the stem and an arc adjustment ring at the upper end of the base. This coil spring biases the rotor plate, shaft, nozzle, deflector and stem to a retracted position relative to the base.
The shaft on which the rotor plate is mounted extends downwardly into and through the deflector, and is provided with an externally threaded metal sleeve fixed to the lower end of the shaft. A throttle member is threadably mounted on the fixed sleeve, so that rotation of the shaft will result in the throttle member moving axially upwardly or downwardly on the shaft, depending on the direction of rotation of the shaft, toward or away from a flow-restriction stop formed near the lower end of the stem. In this way, flow rate to the nozzle, and hence throw radius, can be adjusted as desired. A “slip clutch” mechanism is also provided to protect the throttle assembly in the event of over-rotation of the shaft. Preferably, the arrangement is such that the flow cannot be completely shut off. In other words, even in a position where the throttle member is moved to its maximum restrictive position, enough water is permitted to flow through the base to the nozzle so that the rotor plate continues to rotate, albeit at a slower speed. This preferred configuration is intended to prevent stalling, a condition where the rotor plate ceases rotation as water pressure drops. The throw radius adjustment is effected by rotation of the shaft by a suitable tool engageable with an end of the shaft that is externally accessible to the user. Aside from the flow rate or throw radius adjustment function, the shaft is otherwise rotationally stationary during normal operation, i.e., the rotor plate rotates about the shaft.
In accordance with the '332 patent, the throttle member may be constructed of a suitable urethane rubber and preferably a polyurethane thermoplastic elastomer. Using this material, the interior surface of the throttle member may be left smooth when manufactured, but will resiliently self-tap when engaged by the externally threaded metal sleeve fixed to the lower end of the shaft. This arrangement is particularly advantageous in that, in the event the shaft is over-rotated, the elastomeric throttle member will simply slip over the thread on the metal sleeve, thus creating an effective “slip clutch” that prevents damage to the stem assembly.
In the '332 and '905 patents, the nozzle is rotatably mounted within the base, and cooperates with a stream deflector mounted on the shaft to define an arcuate water discharge orifice. The nozzle is operatively connected through a drive mechanism to the arc adjustment ring mounted on the top of the base, and externally accessible to the user. Thus, the user may rotate the arc adjustment ring to lengthen or shorten the arcuate length of the discharge orifice. It is disclosed that a pair of nozzle/deflector combinations may be employed to provide adjustable arcs between 90° and 210°, and between 210° and 270°. In accordance with another embodiment, the nozzle and deflector are further modified to provide a 360° or full circle pattern.
The arc adjustment feature can be utilized in a pop-up sprinkler only when the rotor plate is extended relative to the base. In other words, components of the drive mechanism are fully engaged only when the nozzle, deflector and stem move upwardly with the rotor plate to engage complementary drive components on the arc adjustment ring. This arrangement prevents accidental arc adjustment when the sprinkler is not in use, e.g., through contact with a lawn mower, weed trimmer or the like. In addition, the arc adjustment ring is configured to permit re-orientation of the sprinkler pattern after the sprinkler is secured to, for example, a fixed, non-rotatable stem or riser in a pop-up assembly.
When used in a pop-up type sprinkler, the sprinklers disclosed in the '332 and '905 patents are extended by a two-stage pop-up mechanism. First, the extendable tube of the pop-up assembly will extend as water under pressure is introduced into the assembly. After the tube extends out of the fixed riser, the rotor plate, nozzle, deflector and stem extend further away from the base at the distal end of the extendable tube so that water emitted from the nozzle can be distributed radially by the rotor plate. This two-stage action is reversed when the flow of water is shut off, so that the rotor plate is in a retracted position that prevents any foreign matter from entering into the nozzle area before the extendable tube of the pop-up assembly is retracted.